1. Field of the Invention
The embodiments discussed herein are directed to a storage apparatus including storage devices, a relay device that controls access to the storage devices, and a method of controlling an operating state of the storage devices.
2. Description of the Related Art
Some disk array apparatus are mounted with a serial attached small computer systems interface (SAS) disk and a serial advanced technology attachment (SATA) disk.
Such a disk array apparatus includes a plurality of housings connected thereto for housing a plurality of hard disk drives (HDDs).
One of the housings, or a controller enclosure, is connected directly to a host computer. Thus, the controller enclosure may be accessed by the host computer, and performs overall control of data storage.
The housings other than the controller enclosure, or device enclosures, may be connected when an HDD is to be added.
Each of the housings includes a processing unit called an expander that relays data between the housings and that performs reading from or writing to an HDD.
When an HDD is added, another device enclosure is connected either to the controller enclosure or to an existing device enclosure with the expanders being communicatively connected.
In the disk array apparatus, for example, write data requested by the host computer is transferred by the expander from the controller enclosure to a device enclosure to which the write data is written, and thus the data is written to an HDD to which the data is written.
A large number of HDDs are mounted on a disk array apparatus that is configured as above, as well as on a general disk array apparatus. Therefore, if power is supplied to all the HDDs, the disk array apparatus consumes excessive amount of power.
In Japanese Laid-open Patent Publication No. 2000-293314, a conventional technology is disclosed in which access made by a host computer is managed for each HDD group (redundant array of independent disks (RAID) group). More specifically, in the conventional technology, access thereto by the host computer is managed so that if a certain RAID group is not accessed by the host computer for a certain period of time, all the HDDs in the RAID group are brought into a power saving mode.
In a disk array apparatus having an SAS disk and an SATA disk mounted thereon also, it is desirable that power consumption thereof be reduced.
The conventional technology is capable of reducing power consumption of such a disk array apparatus having an SAS disk and an SATA disk mounted. However, a state of an HDD is controlled depending on an access interval thereof, and power consumption thereof is not sufficiently reduced. More specifically, the same amount of power is supplied, for example, to an HDD that is not so frequently accessed but that is accessed once during a certain period of time or less and to an HDD that is frequently accessed for a plurality of times during the same period of time.
Besides, in the disk array apparatus, all the HDDs are managed collectively. However, each of the housings includes an expander, and therefore, it is desirable that each of the expanders control a state of each of the HDDs stored in the housings to reduce power consumption so that processing load can be distributed among the expanders.